In recent years, a centralized control network architecture has been proposed. As an example of the centralized control network architecture, a technique called an open flow (OpenFlow) is known. The open flow is implemented by an open flow controller (OpenFlow Controller) and an open flow switch (OpenFlow Switch).
The open flow controller sets a flow table for the open flow switch. The flow table is composed of a flow entry in which a processing rule for a packet belonging to a flow is described. Upon receiving a packet, the open flow switch searches the corresponding flow entry from the flow table, and processes the packet in accordance with the processing rule described in the searched flow entry. Note that when the flow entry is not searched, the open flow controller creates a new flow entry and adds the created flow entry to the flow table.